Polarimeter

ABSTRACT

A sample cell in a polarimeter comprises a thermally conductive body enclosing a substantially cylindrical internal volume with an insulating outer cover which leaves one face exposed for complementarily contacting a temperature controlled base plate so as to keep the sample cell at a predetermined temperature, and a means for positioning the sample cell at a predetermined position such that a measuring light beam longitudinally passes through the sample cell. The water jacket system required for the conventional cylindrical sample cells is eliminated. A cell holder for holding a cylindrical sample cell in a polarimeter comprises a heat transfer element having a concave cylindrical heat transfer surface for complementarily contacting an external cylindrical surface of the cylindrical sample cell so as to keep the sample cell at a predetermined temperature. The heat transfer element is thermally conductive to a thermal electrical conductor element the temperature of which is controllable by an electric current. The cylindrical sample cell is positioned in the light path of the polarized light beam by a cell mount formed by the heat transfer element, or by a pair of flanges resting on a pair of parallel rails. The invention eliminates the use of the water jacket temperature control system for the cylindrical sample cells.

FIELD OF THE INVENTION

[0001] The present invention relates to polarimeters, and moreparticularly, to a sample cell and sample cell holder in which a thermoelectric cooler is used to control the temperature of the sample celland the liquid contained therein.

BACKGROUND OF THE INVENTION:

[0002] A polarimeter is an instrument for measuring the optical activityexhibited by an optically active substance including inorganic andorganic compounds. In particular, the plane of polarization of alinearly polarized light beam is rotated when passing through theoptically active substance, and the rotation is determined by thespecific substance, the concentration of that substance and the opticalpathlength of the light through the substance contained in the samplecell, whereby the concentration of the specific substance can becalculated by the measured rotation. The optical rotation is alsoaffected by the temperature of the substance contained in the samplecell, and thus it is desirable, and in many cases required by governingregulations, that the temperature of the sample substance be controlledto be at a set point for precise measurement.

[0003] As shown in FIG. 1(A) and (B), a sample cell 11 is usually acylindrical tube so as to minimize the amount of the sample substancethat is in the cell but not in the light path, referred to as “deadvolume”. A pair of flanges 15 are provided at opposite ends of thesample cell 11, each with a beam aperture 18 therein for allowing thepolarized light beam (shown as arrow 17) to pass therethrough. Theflanges are usually standard in size for properly positioning the samplecell 11 in the light path when the pair of flanges sit on the cellholder constituted by a pair of parallel rails 16. The flanges may beremovable from the sample cell 11 to facilitate cleaning of the cell.The temperature control of the sample substance is realized bycirculating water in a water jacket 14 around the external surface ofthe sample cell 11 containing the sample substance 12. The water jacket14 is formed by an outer tube 13 communicated with a water tube 19connected to a water source at a predetermined temperature. However,such a water temperature control system is complicated in structure,comprising a water jacket and cooling tubes. Furthermore, it isinconvenient to connect and disconnect the tubing when cleaning the celland changing the sample. It also takes long time to change thetemperature set point.

[0004] Recently, thermoelectric temperature control techniques such asthermo electric coolers (TEC) have been introduced for temperaturecontrol in a polarimeter. The temperature of one side of a TEC device,which is usually a flat plate in shape, is controllable by an electriccurrent. Heat can be made to flow through the device in either directionas required. As shown in FIG. 2, a TEC element 63 with a heat sink 64 isprovided to be thermally conductive with a rectangular cell holder 62accommodating a rectangular sample cell 61. A polarized light beam(shown as arrow 67) passes through the sample cell 11 via the apertures68 provided on the cell holder 12. The solid TEC element 63 eliminatesthe complication and inconvenience of the water tubing required in theconventional cylindrical cell samples. Furthermore, the temperature ofthe cell holder 62 and therefore the sample cell 61 can be easily andquickly controlled at a set point. However, the rectangular sample cell61 assumes a high dead volume and requires a larger sample volume tofill. This is costly when the measured substance is precious. The otherproblem with such a rectangular structural design is that the cellholder 62 can not work with conventional standard cylindrical samplecells which are commonly used in the industry. In addition this designwas not able to control temperature within the limits required byrelevant governing regulations.

SUMMARY OF THE INVENTION:

[0005] An object of the invention is to provide a sample cell with asubstantially cylindrical internal volume with its temperaturecontrollable by a TEC element.

[0006] A further object of the invention is to provide a cell holderwhich is capable of holding both the inventive sample cell in atemperature controlled mode and conventional standard cells which arenot temperature controlled by the cell holder. These conventional cellsmy be either of the water jacketed temperature controlled type or thenon jacketed, non temperature controlled type.

[0007] A further object of the invention is to provide a cell holder forholding cylindrical sample cells with its temperature controllable by aTEC element.

[0008] A further object of the invention is to provide a cell holderwith TEC temperature control unit which is capable to work with theconventional standard sample cells currently in common use.

[0009] To achieve the above objects, the sample cell of the presentinvention comprises a thermally conductive body enclosing asubstantially cylindrical internal volume with an insulating outer coverwhich leaves one face exposed for complementarily contacting atemperature controlled baseplate so as to keep the sample cell at apredetermined temperature, and a means for positioning the sample cellat a predetermined position such that a measuring light beamlongitudinally passes through the sample cell.

[0010] Thus, the temperature of the sample cell, which is less in deadvolume, is controlled by the temperature control means. The water jacketsystem required for the conventional cylindrical sample cells iseliminated.

[0011] Preferably, the base plate which is fixedly positioned relativeto the light path of the light beam for positioning purposes, istemperature controlled by means of being thermally conductive with a TECelement.

[0012] In a preferred embodiment, the heat transfer element is a cellmount on which the cylindrical sample cell rests. The cell mount isplaced on the base plate in a predetermined position.

[0013] Preferably, the base plate comprises a slant upper surface onwhich the cell mount rests, and the cell holder further comprises ahorizontal rail. The rail, on the one hand, stops the cell mount at apredetermined position on the base plate, and on the other hand, enablesthe inventive cell holder capable of supporting a conventional standardcylindrical sample cell by supporting its flanges directly resting onthe rail and the slant upper surface of the base plate.

[0014] In another preferred embodiment, the heat transfer element is acover resting on the cylindrical sample cell which sits on a pair ofparallel rails. Preferably, the heat transfer element is detachablyconnected to the base plate so that the base plate can work withdifferent heat transfer elements for different sizes of cylindricalsample cells.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0015] The above and other advantages and features of the presentinvention will be clearer from the following detailed description of thepreferred embodiment of the present invention with reference to theaccompanying drawings, in which:

[0016] FIGS. 1(A) and 1(B) are perspective and sectional viewsrespectively of a prior art conventional standard cylindrical samplecell and the positioning rails supporting the sample cell;

[0017]FIG. 2 is a perspective view of a prior art rectangular cellholder for holding a rectangular sample cell with a TEC element fortemperature control;

[0018] FIGS. 3(A) and 3(B) are perspective and sectional viewsrespectively of a first embodiment of the cell holder according to thepresent invention;

[0019] FIGS. 4(A) and 4(B) are perspective and sectional viewsrespectively of the first embodiment in FIGS. 3(A) and 3(B) when usedwith a conventional standard cylindrical sample cell;

[0020] FIGS. 5(A) and 5(B) are perspective and sectional viewsrespectively of a second embodiment of the cell holder according to thepresent invention;

[0021] FIGS. 6(A) and 6(B) are perspective and sectional viewsrespectively of a third embodiment of the cell holder according to thepresent invention;

[0022] FIGS. 7(A) and 7(B) are perspective and sectional viewsrespectively of a fourth embodiment of the cell holder according to thepresent invention;

[0023] FIGS. 8(A) and 8(B) are perspective and sectional viewsrespectively of a fifth embodiment of the cell holder according to thepresent invention; and

[0024]FIG. 9 shows an alternative embodiment of the invention whereinthe portion of the cell holding the sample and the surrounding materialare integral with each other.

DETAILED DESCRIPTION OF THE INVENTION:

[0025] The invention is now described in detail with reference to thepreferred embodiments shown in FIGS. 3-9 in which the same numerals areused for designating similar elements.

[0026] A cell holder according to the first embodiment of the presentinvention is illustrated in FIGS. 3(A) and 3(B). The cell holdercomprises a cell mount 22 having a concave cylindrical surface forcomplementarily accommodating a cylindrical sample cell 11 therein. Thecell mount 22 rests on a base plate 21 under which a thermal electricconductor (TEC) element 23 is attached. Both the cell mount 22 and thebase plate 21 are made of thermally conductive materials so that thetemperature of the cell mount 22 and therefore its concave cylindricalsurface is controlled by the TEC element 23. With the concavecylindrical surface of the cell mount 22 as a heat transfer surface, thesample cell 11 is thermally conductive with the TEC element 23, wherebyits temperature is kept the same as the TEC element 23 which iscontrolled at a set point by an electric current. TEC element 23 isprovided with heat sink 24 comprising plurality of cooling fins.

[0027] The base plate 21 is fixedly secured in its position relative tothe light path of the measuring polarized light beam (shown as arrow 17)for the purpose of the positioning of the sample cell 11 supported bythe cell mount 22. As shown in FIGS. 3(A) and 3(B), the base plate 21assumes a tilted posture such that its upper surface is slanted. Asingle horizontal rail 16 is provided parallel to the slant uppersurface of the base plate 21, also for the positioning of the samplecell 11, which will be described in detail below.

[0028] The sample cell 11 is provided with a pair of circular flanges 15each with a central aperture 18 for the light beam 17 to pass throughthe sample substance 12 contained in the sample cell 11. The flanges 15abut on the rail 16, whereby the cell mount 22 is stopped at apredetermined position from further movement along the slant uppersurface of the base plate 21. It is noted that the flanges 15 are partlyremoved at 15 a so that they will not touch the slant upper surface ofthe base plate 21. Thus, the positioning of the sample cell 11 isrealized by the contact between the flanges 15 and the rail 16 as wellas by the contact between the cell mount 22 and the slant upper surfaceof the base plate 21.

[0029] An enclosing member 25 is provided to form, together with theconcave cylindrical surface of the cell mount 22, a longitudinallycomplete enclosure for the sample cell 11. The enclosing member 25 maybe attached to the cell mount 22, e.g., by a hinge connection 26. Theenclosing member 25 is made of a thermally insulating material forpreventing the sample cell 11 from exposure to ambient environment.

[0030] Alternatively, the enclosing member 25 may be made of a thermallyconductive material for enhancing the heat transfer between the cellmount 22 and the sample cell 11. Preferably, a concave surface may beformed in the internal surface of the enclosing member 25 tocomplimentarily covering on the sample cell 11.

[0031] One important advantage of the cell holder in FIGS. 3(A) and 3(B)is that it is also capable of working with the conventional standardcylindrical sample cells with or without a water temperature controlsystem. As shown in FIGS. 4(A) and 4(B), the pair of flanges 15 of aconventional standard cylindrical sample cell 11 can directly sit on thesingle rail 16 and the slant upper surface of the base plate 21. Thepositioning of the sample cell 11 is realized by the contact between theflanges 15 and the rail 16 as well as by the contact between the flanges15 and the slant upper surface of the base plate 21.

[0032] Thus, the cell holder shown in FIGS. 3(A) and 3(B) can work withboth the conventional standard cylindrical sample cells with waterjacket temperature control system that are currently vastly used in theindustry, and the novel cylindrical sample cell 11 with its flangespartly removed as shown in FIGS. 3(A) and 3(B).

[0033] Another embodiment of the cell holder is shown in FIGS. 5(A) and5(B), in which the rail 16 directly abuts against a side surface of thecell mount 22 to stop it at a predetermined position on the slant uppersurface of the base plate 21. The cylindrical sample cell 11 in thisembodiment does not need the flanges, thus substantially decreasing thecost of manufacture. The positioning of the sample cell 11 is alsoimproved as there is no force applying to the sample cell from theflanges as in the case shown in FIGS. 3 (A) and 3(B).

[0034] In this embodiment, the upper surface of the cell mount 22 onwhich the concave cylindrical surface is provided is generallyhorizontal so as to stably support the sample cell 11 thereon. A pair ofcaps 20 with light beam apertures 18 are provided at its opposite endsfor facilitating the cleaning of the sample cell. The cell holder inthis embodiment is also capable to work with conventional standardcylindrical sample cells as shown in FIGS. 4(A) and 4(B).

[0035] Temperature sensors may be used via insertion in the sample celland/or permanently embedding such sensors in the base plate inaccordance with known techniques. Such techniques, and others, are knownin the art and not described in detail herein.

[0036] FIGS. 6(A) and 6(B) illustrate a cell holder according to a thirdembodiment of the present invention, in which the base plate 21 ishorizontally positioned, thus eliminating the need of the rail 16 inFIGS. 3-5. The cell mount 22, which supports the cylindrical sample cell11 in its concave cylindrical heat transfer surface, rests on thehorizontal upper surface of the base plate 21. Same as in theembodiments in FIGS. 3-5, the base plate 21 is fixedly secured inposition relative to the light path for the purpose of the positioningof the cell mount 22 and therefore of the sample cell 11. To prevent thelateral movement of the cell mount 22, a stopper 27, which may be in theform of a side wall, is provided on the upper surface of the base plate21 to stop the cell mount 22. A bias spring force may also be providedto ensure the cell mount 21 abut against the stopper 27 (see FIG. 6(B)).

[0037] FIGS. 7(A) and 7(B) illustrate a cell holder according to afourth embodiment of the present invention, which is similar to thatshown in FIGS. 6(A) and (B), and thus only the different features aredescribed here. In this embodiment, the positioning of the cell mount 22on the base plate 21 is realized by multiple positioning pin-holeconnections 28 (two of them are shown in FIG. 7(B)) instead of thestopper 27. It is also noted that the TEC element 23 is shown to beattached to the side wall of the base plate 21 in this embodiment.

[0038] A cell holder according to a fifth embodiment of the presentinvention is shown in FIGS. 8(A) and 8(B). Unlike the previousembodiments shown in FIGS. 3-7, the TEC temperature control unit in thisembodiment is implemented as a heat transfer element that covers on thecylindrical sample cell 11. In particular, the base plate 21 in thisembodiment is not secured relative to the beam light path as in theprevious embodiments, and thus has no positioning function.

[0039] The TEC temperature control unit in this embodiment comprises aheat transfer element 22 which is provided with a concave cylindricalheat transfer surface for complimentarily covering on the externalsurface of the cylindrical sample cell 11. The heat transfer element 22is detachably connected with the base plate 21, e.g., by a dove-tailconnection 29, so that the base plate 21 may connect with different heattransfer element 22 for different sizes of the sample cells 11. A TECelement 23 is attached to the base plate 21 for providing temperaturecontrol to sample cell 11 through the base plate 21 and the heattransfer element 22. The temperature of the TEC element 23 iscontrollable at a predetermined point by an electric current as wellknow in the art. The TEC element 23 is also provided with heat sink 24comprising multiple cooling fins.

[0040] In this embodiment, the TEC temperature control unit may beprovided as a separate device that is physically independent of thepolarimeter, since it does not interfere with the positioning of thesample cell 11.

[0041] The positioning of the cylindrical sample cell 11 in thisembodiment is realized solely by a pair of parallel rails on which apair of flanges 15 sit, just as in the conventional way shown in FIGS.1(A) and 1(B). Therefore, the cell holder in this embodiment also workswell with the conventional standard cylindrical sample cells. Unlike theembodiment shown in FIGS. 3(A) and 3(B), the flanges 15 here are fullcircular in shape and do not need to be partly removed.

[0042]FIG. 9 shows an additional embodiment of the present invention inwhich a cylindrical bore 901 is surrounded by material 902. Theembodiment of FIG. 9 is somewhat different from the other embodiments inthat the surrounding material 902 is not a separate portion that getsconnected to the cell. Instead, the material 902 and bore 901 are formedfrom a single integral part. Notably, as used herein the concavecylindrical heat transfer surface that contacts the cell is intended tocover the junction between the material 902 and the bore 901 in the caseof embodiments such as those of FIG. 9, wherein the two are made from asingle part.

[0043] The above has described the preferred exemplary embodiments ofthe present invention. It shall be appreciated, however, that numerousalternations, modifications and changes are possible to those skilled inthe art without departing the gist of the present invention. Forexample, in the embodiment in FIGS. 5(A) and (B), a block may beprovided on the slant upper surface of the base plate 21 for the purposeof, as an alternative to the rail 16, stopping the cell mount 22 at thepredetermined position. In the embodiment in FIGS. 8(A) and 8(B), thebase plate 21 can be eliminated if the heat transfer element 22 isconnected directly to the TEC element 23 to form an integral device foreach size of the cylindrical sample cell 11. Therefore, the scope of theinvention is to be solely defined by the accompanying claims.

What is claimed is:
 1. A cell holder for holding a cylindrical samplecell in a polarimeter, comprising: a thermal electric conductortemperature control means in contact with a concave cylindrical heattransfer surface for complementarily contacting an external cylindricalsurface of said cylindrical sample cell so as to keep said sample cellat a predetermined temperature; and a positioning means for positioningsaid cylindrical sample cell at a predetermined position such that apolarized light beam longitudinally passes through said sample cell. 2.The cell holder of claim 1, wherein said thermal electric conductortemperature control means comprises a thermal electric conductor elementthat is made of thermal electric conductor material, a temperature ofwhich is controllable by an electric current.
 3. The cell holder ofclaim 2, wherein said thermal electric conductor temperature controlmeans further comprises a heat transfer element having said concavecylindrical heat transfer surface and being thermally conductive withsaid thermal electric conductor element.
 4. The cell holder of claim 3,wherein said heat transfer element is made of a thermally conductivematerial.
 5. The cell holder of claim 4, wherein said heat transferelement is thermally conductive to said thermal electric conductorelement through a base plate.
 6. The cell holder of claim 5, whereinsaid heat transfer element is detachably connected to said base plate.7. The cell holder of claim 6, wherein said heat transfer element isdetachably connected to said base plate by a dovetail connection.
 8. Thecell holder of claim 5 wherein said base plate is fixedly secured inposition relative to a polarized measuring light beam that passesthrough said cylindrical sample cell.
 9. The cell holder of claim 8wherein said cell mount is provided with a flat surface opposite to saidconcave cylindrical heat transfer surface so as to rest on a flatsurface of said base plate.
 10. The cell holder of claim 9 furthercomprising a positioning means for keeping said cell mount in a positionrelative to said base plate.
 11. The cell holder of claim 3 wherein saidheat transfer element further comprises an enclosing member to form,together with said concave cylindrical surface, a longitudinallycomplete enclosure around said sample cell for keeping said sample cellapart from ambient temperature.
 12. The cell holder of claim 11 whereinsaid enclosing member is made of a thermal insulation material.
 13. Thecell holder of claim 12 wherein said enclosing is made of a thermalconductive material.
 14. The cell holder of claim 2 wherein said thermalelectric conductor element comprises a heat sink having multiple coolingfins.
 15. The cell holder of claim 4 wherein said heat transfer elementis a cover placed on said cylindrical sample cell with said concavecylindrical surface engaging with an external cylindrical surface ofsaid sample cell.
 16. The cell holder of claim 15 wherein saidpositioning means comprises a pair of parallel arranged rails forsupporting said cylindrical sample cell thereon.
 17. The cell holder ofclaim 16 wherein said cylindrical sample cell comprises a pair of flangeat its opposite ends for sitting on said pair of rails.
 18. A cellholder for holding a cylindrical sample cell in a polarimeter,comprising: a cell mount having a concave cylindrical surface forcomplementarily accommodating a cylindrical external surface of saidcylindrical sample cell, said cell mount being made of a thermallyconductive material, and a temperature control unit being thermallyconductive with said cell mount so as to keep said concave surface at apredetermined temperature.
 19. The cell holder of claim 18 wherein saidtemperature control unit comprises a thermo electric cooler (TEC)element with a temperature controllable by an electronic circuit. 20.The cell holder of claim 19 further comprising a base plate forsupporting said cell mount in a predetermined position such that apolarized light beam passes through said cylindrical sample cell formeasuring optical activities of a sample contained in said sample cell.21. The cell holder of claim 20 wherein said base plate is fixedlysecured relative to said polarized light beam.
 22. The cell holder ofclaim 21 wherein said cell mount is provided with a flat surfaceopposite to said concave cylindrical surface so as to rest on a flatsurface of said base plate.
 23. The cell holder of claim 22 wherein saidflat surface of said base cell is a slant surface forming a slope. 24.The cell holder of claim 23 further comprising a positioning means forkeeping said cell mount in said predetermined position when said cellmount rests on said base plate.
 25. The cell holder of claim 24 whereinsaid positioning means comprises a rail longitudinally parallel to saidconcave cylindrical surface of said cell mount resting on said baseplate.
 26. The cell holder of claim 25 wherein said rail is positionedto abut a side wall of said cell mount for preventing said cell mountfrom sliding down along said slant surface of said base plate.
 27. Thecell holder of claim 26 wherein said cell mount, while resting on saidslant surface of said base plate, comprises a substantial horizontalupper surface on which said cylindrical concave surface is provided. 28.The cell holder of claim 25 wherein said rail is positioned to abut apair of flanges provided at opposite ends of said cylindrical samplecell while said sample cell is accommodated in said concave cylindricalsurface of said cell mount resting on said base plate.
 29. The cellholder of claim 28 wherein said flanges is partly removed such that saidflanges do not contact said flat surface of said base plate.
 30. Thecell holder of claim 29 wherein said rail is positioned such that, whensaid sample cell with a pair of full-circular flanges at opposite endsrests directly on said slant flat surface of said base plate and saidrail, said light beam passes through said sample cell.
 31. The cellholder of claim 30 wherein said cylindrical sample cell is aconventional standard sample cell having a water jacket for temperaturecontrol.
 32. The cell holder of claim 22 further comprises a positioningmeans for keeping said cell mount in said predetermined position. 33.The cell holder of claim 32 wherein said positioning means comprises astopper to restrain said cell mount resting on said base plate from ahorizontal movement in a lateral direction.
 34. The cell holder of claim33 wherein said positioning means further comprises a bias spring toforce said cell mount to abut against said stopper.
 35. The cell holderof claim 21 wherein said cell mount is connected to said base plate bymeans of a detachable connection.
 36. The cell holder of claim 35wherein said detachable connection is a dovetail connection.
 37. Thecell holder of claim 35 wherein said detachable connection is a pin-holeconnection.
 38. The cell holder of claim 20 wherein said base plate ispositioned between said thermal electric conductor element and said cellmount for heat conduction between said thermal electric conductorelement and said cell mount.
 39. The cell holder of claim 38 whereinsaid thermal electric conductor element is provided with a heat sinkcomprising multiple cooling fins.
 40. The cell holder of claim 18further comprising a cover to form, together with said concavecylindrical surface, a longitudinally complete enclosure around saidsample cell for keeping said sample cell apart from ambient temperature.41. A cell holder for a cylindrical sample element in a polarimeter,comprising: a base plate fixed secured in position relative to apolarized measuring light mean passing through said sample element, saidbase plate having a slant flat surface; and a horizontal rail parallelto said slant flat surface of said base plate.
 42. The cell holder ofclaim 41 wherein said a temperature of said slant surface is controlledby a temperature control unit.
 43. The cell holder of claim 42 whereinsaid temperature control unit comprises a thermal electric conductorelement which temperature is controllable by an electric circuitry. 44.The cell holder of claim 43 wherein said rail is positioned such that,when said sample cell sits directly on said slant flat surface of saidbase plate and said rail, said light beam passes through said samplecell.
 45. The cell holder of claim 44 wherein said cylindrical samplecell is a conventional standard sample cell having a sample chambercontaining sample substance and a water jacket around said samplechamber for temperature control.
 46. The cell holder of claim 45 whereinsaid conventional standard sample cell comprises a pair of full-circularflanges at opposite ends for sitting directly on said slant flat surfaceof said base and said rail.
 47. The cell holder of claim 43 furthercomprising a cell mount having a concave cylindrical surface forcomplimentarily accommodating said cylindrical sample cell.
 48. The cellholder of clam 47 wherein said cell mount is made of a thermallyconductive material, and comprises a flat surface opposite to saidconcave cylindrical surface so as to rest on said slant flat surface ofsaid base plate.
 49. The cell holder of claim 48 wherein said rail ispositioned to abut a pair of flanges provided at opposite ends of saidcylindrical sample cell while said sample cell is accommodated in saidconcave cylindrical surface of said cell mount resting on said baseplate.
 50. The cell holder of claim 49 wherein said flanges is partlyremoved such that said flanges do not contact said flat surface of saidbase plate.
 51. The cell holder of claim 50 wherein said sample cellcomprises a sample chamber for containing a sample substance, saidsample chamber having an external cylindrical surface forcomplimentarily engaging with said concave cylindrical surface of saidcell mount.
 52. A sample cell for containing a sample substantive formeasurement in a polarimeter, comprising: a cylindrical tube forming asample chamber for containing said sample substantive, wherein said tubebeing made of a thermally conductive material and having a cylindricalexternal surface exposed directly to an ambient environment.
 53. Thesample cell of claim 52 further comprising a pair of flanges for sealingsaid sample chamber at its opposite ends.
 54. The sample cell of claim53 wherein each of said flanges is provided with a central hole for apolarized measurement light beam to pass therethrough.
 55. The samplecell of claim 54 wherein each of said flanges is partly removed.
 56. Atemperature control apparatus for controlling a temperature of acylindrical sample cell in a polarimeter, comprising a concavecylindrical heat transfer surface for complementarily engaging with anexternal cylindrical surface of said cylindrical sample cell, and atemperature control unit for controlling a temperature of said heattransfer surface at a predetermined temperature.
 57. The temperaturecontrol apparatus of claim 56 wherein said temperature control unitcomprises a thermal electric conductor element which temperature iscontrollable by an electric circuitry.
 58. The temperature controlapparatus of claim 57 wherein said heat transfer surface is provided ona heat transfer element.
 59. The temperature control apparatus of claim58 further comprising a base plate for thermally conductive between saidheat transfer element and said thermal electric conductor element, saidbase plate being made of a thermally conductive material.
 60. Thetemperature control apparatus of claim 59 wherein said heat transferelement is a cell mount for supporting said sample cell on said concavesurface.
 61. The temperature control apparatus of claim 60 wherein saidbase plate is fixed secured in position relative to a polarizedmeasuring light beam that passes through said sample cell.
 62. Thetemperature control apparatus of claim 61 wherein said cell mount havinga flat surface.
 63. The temperature control apparatus of claim 62wherein said heat transfer element is a cover placed on said cylindricalsample cell with said concave cylindrical heat transfer surface engagingwith an external cylindrical surface of said sample call, said coverbeing made of a thermally conductive material.
 64. The temperaturecontrol apparatus of claim 63 further comprising a base plate forthermally conductive between said heat transfer element and said thermalelectric conductor element, said base plate being made of a thermallyconductive material.
 65. The temperature of claim 64 wherein said heattransfer element is connected to said base plate through a detachableconnection.
 66. The temperature of claim 65 wherein said detachableconnection is a dove-tail connection.
 67. The temperature of claim 66wherein said thermal electric conductor element further comprises a heatsink having multiple cooling fins.
 68. The temperature of claim 67further comprising an enclosing member to form, together with saidconcave cylindrical surface, a longitudinally complete enclosure aroundsaid sample cell for keeping said sample cell apart from ambienttemperature.
 69. The temperature of claim 68 wherein said enclosingmember is made of a thermally insulation material.
 70. The temperatureof claim 69 wherein said enclosing member is made of a thermallyconductive material.
 71. A polarimeter for measuring optical activitiesof a sample substance, comprising: a sample cell for accommodating saidsample substance to be measured, said sample cell being made of athermally conductive material and having a positioning means on an outersurface thereof for positioning said sample cell in a predeterminedposition such that a polarized measurement light beam passeslongitudinally through said sample cell; and a temperature control unithaving a planar heat transfer surface for contacting external surface ofsaid sample cell so as to keep said sample cell at a predeterminedtemperature, and an additional nonplanar surface to aid in positioningsaid sample cell.
 72. The polarimeter of claim 71 wherein saidtemperature control unit comprises a thermal electric conductor element.